The LAN settings are the ones you want, assuming you want DNS servers other or in addition to the ones your ISP provides you. They set the WAN DNS servers that the LAN hosts use directly or indirectly depending on your settings in Advanced>DHCP/DNS.

Setting WAN type to "Static" does not disable the "Static DNS" servers option - it is still available in the LAN section (as those are the DNS servers to be used for your LAN, and they are independent from the WAN connection type).